Manufacture of photographic materials



Oct. 26, 1965 Filed 001;.

' FIG.I.

FIG.2.

FIG.3.

FIG.4.

FIG.5.

FIG.6.

YASUSHI OHYAMA ETAL 3,214,274

MANUFACTURE OF PHOTOGRAPHIC MATERIALS 17, 1961 2 Sheets-Sheet l MECHANISM OF PORE FORMATION DEW DROP BEGINNING OF DEW DROP ON SUBBING LAYER (STILL WET) RESIN SOLVENT PORE (INITIAL STAGE) PORE FORMATION PORE (FINAL STAGE) (COMPLETELY DRIED) &\\\\\\\\ DRIED RESIN LAYER MOLDING ST (HALF DRIE TOP PLAN VIEW OF A PORE PENING OF PORE CROSS SECTIONS OF A PHOTOGRAPHIC MATERIAL PHOTOGRAPHIC EMULSION CHYDROPHIL I IIY EQ PIILCI SUBBING LAYER BACKING LAYER (ANTI"' HALATION, HYDROPHILIC) W PHOTOGRAPHIC EMULSION MICRO-PORES SUBBING LAYER INVENTORS Yosushi Ohyumu, Syuichi Maruyoma gww,fi ,%'fl%g%w a ORNEYS BASE SHEET Och 1965 YAsusHl OHYAMA ETAL 3,214,274

MANUFACTURE OF PHOTOGRAPHIG MATERIALS Filed Oct. 17, 1961 2. Sheets-Sheet 2 k 6Q t m5 \wtmw Q Q As QER QS i mgmw w INVENTORS a w ZWJ im t. A %M D D w mw a ELEM,

United States Patent 3,214,274 MANUFACTURE OF PHOTOGRAPHIC MATERIALS Yasushi Ohyama and Syuichi Maruyama, both of Kaiden, Nagaolramachi, Otokuni-gun, Kyoto, Japan, assignors to Mitsubishi Paper Mills, Ltd., Tokyo, Japan, a corporation of Japan Filed Oct. 17, 1961, Ser. No. 145,733 Claims priority, application Japan, Oct. 19, 1960, 35/41,682; Aug. 18, 1961, $609,396 11 Claims. (Cl. 96-85) This invention relates to the manufacture of photographic materials having a highly hydrophobic film base composed of polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, poly-aorylonitrile and the copolymer of the monomeric compounds chiefly composed of the above mentioned polymers and polyesters such as polyethylene terephthalate .and the modified derivatives of it or the base made of cloth, paper or other things impregnated or coated with the above mentioned synthetic resins.

In applying a layer such as a photographic emulsion layer, transfer layer or backing layer on the hydrophobic base, it is known that one or more interlayers of special compositions must be applied to promote aflinity between the hydrophobic base and the hydrophilic photographic layer which is usually composed of a highly hydrophi-lic colloid such as gelatine or polyvinyl alcohol.

Frequently, satisfactory adhesion ,of such a coating cannot be obtained with :a single inter-layer, and it is necessary to apply two or three layers of different compositions, all of which increases the time and expense in the production.

On the other hand, this invention requires just one layer of coating tor the purpose of securing the desired complete and augmented adhesion between the hydrophobic base and the hydrophilic colloid layers applied on the base of photographic materials thereby providing igiost excellent surf-ace property on the most economical I ass.

This invention renders the maufactu-re of photographic materials doubly economical due to the low-cost of the materials to be utilized and the fewer steps in the production.

This invention provides highly dimensionally stable photographic materials which are not affected by the moisture content in the air or by treatments in aqueous photographic processing solutions (such as developing, 1fjixing, washing, etc.), by use of a highly hydrophobic l ase.

Furthermore, this invention is characterized in providing photographic materials suitable for a rapid processing by use of a highly hydrophobic film base and also, as it will be mentioned later, a master paper suitable for offset printing.

Other characteristic features of this invention are set out below: This invention specifies that the synthetic resin solution of the copolymer mainly composed of vinylidene chloride and copolymerized with vinyl chloride or acrylonit-rile or the like will be applied on one side or both sides of the above-mentioned highly hydrophobic base. The solvent for this solution specified in the invent-ion is the mixture of aromatic hydrocarbons such as benzene, toluene, xylene or the like, and ketones such as acetone, methyl ethyl ketone, methylisop-ropyl ketone or the like. It is preferred that the mixed solvent include 30-50% by Weight ofacetone. Upon application, the hydrophobic base which is coated with the above mentioned solution of resin will be chilled to mold a thin film coating in a comparatively low temperature lair current at 50-85 F. whose velocity is 0.5-4 m./sec., and relative humidity is more than 70%. The coating which is specified will turn out to be a thin of coating spread over the face of the hydrophobic base materials with an innumerable amount of micro minute flat pores of about 0.1-1 micron each in diameter, whose tops are open and hollow round inside. This thin .coating with its surface formed of myriads of micro-pores or holes acts as an inter-layer or subbing layer for the photographic layer, i..e., hydrophilic colloid layer basically consisting of gel'atine, polyvinyl alcohol and the like which is applied over it.

This invention is further exemplified in the accompanying drawings. FIGURE 1 shows in cross section greatly enlarged, but not to scale, a typical dew droplet as just formed on the surface of the still-wet subbing layer.

FIGURE '2 shows the partially formed pore during the next stage of the process, when the resin of the subbing layer has set up but not completely dried.

FIGURE *3 shows the completely hardened and dried film with a typical button-shaped pore.

FIGURE 4 is a surface view of the film of FIGURE .3, looking into the pore.

FIGURE 5 is a magnified view, in vertical section, not to scale, of photographic article made in accordance with the invention showing the hydrophobic base sheet with a hydrophilic coating in each side thereof anchored thereto by the subbing layers.

FIGURE 6 is a further enlarged sectional view of a portion of the base sheet with the subbing layer and outer photographic emulsion coating. I-Iere the enlargement is sufficient to show the micropores on the upper surface of the subbing layer.

FIGURE 7 is a diagrammatic flow sheet illustrating the complete process as described herein, starting with the hydrophobic film base and ending with the finished photographic article after application of the several layers to the base.

Appropriate legends on all these figures render them self-explanatory.

The gist of this invention lies in the fact that benzene, toluene, xylene are comparatively slow to evaporate and sparingly soluble in water, while on the contrary, acetone, methyl ethyl ketone and the like are not only easily volatile but easily soluble in water, consequently, when the coatings are exposed to an air current of high humidity and relatively low temperature, the solution will quickly evaporate into the air stream thereby cooling the coating tothe dew point of the air with the simultaneous for mation of a large number of micro-minute dew drops on the surface of coating, and the dew drops will dissolve ketone and the like which are very soluble in water, expanding into the interior part of the coating, at the same time, when large part of evaporable ketone and the like and some part of sparingly evaporable and water-incompatible benzene, toluene or the like have evaporated, the coating of the synthetic resin, -i.e., the copolymer basically composed of vinylidene chloride will be gelled creating a very considerable number of roughly spheric hollow holes or pores on the surfiace, filling them with dew which can be brought forth from dissolution of ketone or the like.

When the coating is completely dried upon exposure to the warm current after above rnentioned processes, the solvent will leave from condensation of moisture the air and the coating, and as it goes, the film will gradually contract only in the direction perpendicular to the surface of the film (the contraction can not be performed in other directions because the coating closely attached to the base). This contraction will iflatten the spher-ic holes which are hollow inside and eifect formation of beret like shape of each spheric pore opened at the top and round inside.

The photographic layer composed of gelatine, polyvinyl alcohol or the like, upon application to this microporous surface, penetrates the pores thereof. The thusapplied layer then will cling to the inter-layer even though there is no chemical affinity between two layers. The second 'l-ayer (photographic layer) will fill and adhere to all orifices in what looks like rnicro needles or rivets implanted all over the coating film face, thus making 'the .two layers closely adhere in a 'very 'stable permanent b ond.

Each element, such as humidity, wind velocity and quantity of ketone or the likeparticularly acetonein the solvent has an effect on the performance of this invention. If the humidity in the air which contributes the condensation of dew drops in the cooling process is relatively low, the resulting pores will be too few and too shallow in shape, even if the dew point could be reached. Adhesivity will be spoiled in this case. If the humidity in the air is excessive, the dew droplets will interconnect each other and form in undesirably large shape, often causing a stream to flow over the still wet and unfixed coating surface and resulting in lines and stripes on the coating surface. The market value of this kind of commodity will be very low.

The velocity of the air flow to be utilized for this invention is another important requirement. A current of too low a velocity cannot promote the speedy absorption of evaporation heat to reach the dew point of the air. Dew will not be formed and the invention will not be completed. If the air flow is too strong, the dew may flow in undesirable patterns on the surface of the coating. If the proportion of the ketones of low boiling point, especially that of acetone, were less than indicated, the air will not be cooled enough to reach the dew point and if the proportion of acetone is too much, gelation of the film may be retarded whereby the droplets of the condensed water coalesce and the flow so that it goes under the surface of the film and the dew drops will not have their open spheric holes thus created on the photographic film depend upon the kind of resin utilized and conditions of the procluction. However, those holes are, in general, very minute, as small as 0.11 micron each in diameter, hardly detectable by optical microscope and exactly observable only through electron microscope. The minute spheric holes are aligned and spread closely and evenly on the surface of the base film appearing milky white like a frosted glass. When the photographic layer is applied on top of this coating, the hydrophilic colloid fills all holes and voids, thus making complete transparency by eliminating diffused refiexion, because the reflection index of the photographic layer is almost equal to that of the coated resin layer after drying. The photographic film made according to this invention, accordingly, is adapted to projection for enlarging and viewing as Well as other photographic purposes.

The micro-pores produced on the surface of the subbing layer according to this invention are individually quite small, in the order of 0.11.0 micron in diameter as above noted, and average in the order of per square centimeter.

The resin for the subbing layer preferably is composed of from 5090% vinylidene chloride copolymerized with vinyl chloride or acrylonitrile. Small amounts of vinyl acetate or malic anhydride may also be included if desired. Suitable synthetic resins of this type available commercially are: Alon 321 and Alon 781 of the T021 Gesi Kabushiki Kaisha or Saran F420, Saran 1 -220 and Saran F 242 of the Dow Chemical Co., USA.

For the base of photographic film, the most popular and 4 important are polyester base film called Mylar, Cronar (both are Du Pont products), i.e., polyethylene terephthalate, hard polyvinyl chloride film, copolymer base film composed of vinyl chloride and vinyl acetate, Astralon (product of Dynamit A6.) or Saran film, i.e., copolymer of vinyl chloride and acrylonitrile.

In addition to such plastic film bases, the subbing layer may also be applied to other forms and materials of supporting base and paper, tracing paper, tracing cloth or the like, inclusive of Japanese paper and glass cloth, also soca-lled non-woven fabric or synthetic paper made of pulplike substances, comprised of synthetic resin fibres such as nylon, polyvinyl chloride, polyvinyl acetal, polyacrylonitrile, polyethylene terephthalate, polypropylene or the like, impregnated or coated with the aforementioned highly hydrophobic synthetic resins.

These plastic bases are quite strong, waterproof, and dimensionally stable, thus adapted for the photographic reproduction of engineering and industrial drawings. Most of them are transparent or translucent and thus are quite suitable as the base material for reproduction of diapositive or intermediate pictures. However, they have had far from popular use due to the ditficulties in coating the photographic films on them.

The nature and scope of the invention will be more readily understood from the following specific examples.

Example 1 Dissolve 60 grams of Alon 781 (a product of the Toa Gosei Kabushiki Kaisha) purchable at market, which is the copolymer of vinylidene chloride and vinyl chloride, into 600 grams of synthetic solvent of acetone-toluene (mixed at ratio of 1:1) and apply the solution for subbing on one side of the film base made of 0.10 mm. thick polyethylene terephthalate at the speed rate of under 4 m./mm., then expose to an air current at 63 F. with the relative humidity of 70%, whereby the air moisture condenses on the surface, then dry in a current of heated dry air. Then apply on the face the photographic emulsion of the conventional gelatine colloid type in the usual way. A photographic material for microfilming is produced by applying to the base material prepared by the abovedescribed process a photographic emulsion made from the following solutions:

Solution A (150 F.):

Water ml 1200 Photographic gelatine grams 40 "Potassium bromide do 34 Sodium chloride do 36 Cadmium chloride do 2 Citric acid do 2 SolutionB (140 F):

Silver nitrate grams Water ml 1000 Solution C (150 F.):

Photographic gelatine grams 200 Water ml 1000 Add the solution B to A while constantly stirring the mixture. At 30 seconds later, add solution C to the mixture. Digest the mixture for 20 minutes at 150 F., then cool it down to chill and wash for about 2 hours. After further adding 60 grams of gelatine, digest the mixture for 50 minutes at F. Then cool it to 100 F. and add 50 ml. of 0.1% sensitizing dye solution and other ingredients for coating aid.

Example 2 The usual antihalation backing may also be applied to the film produced according to Example 1. To do so it is only necessary to form the microporous surface on the back of the plastic film base also before application of the conventional gelatine solution which contains a coloring matter that serves as the discoloring agent elfective during development processing.

Example 3 Polyethylene terephthalate film base (obtainable on market as Mylar, a product of Du Pont) of 0.075 mm. thickness can be reinforced at its back side by applica tion of the solution combination whose major component is aqueous latex of synthetic resin such as Polysol EV-S (Kobunshi Kogyo K.K. pro-duct) basically consisting of vinylidene chloride and a small proportion of watersoluble colloid and rice starch, for the purpose to mold up the mat that prevents the curling of the film back. The film base will be dried upon application of said solution, then its face is coated with a solution of 90 grams vinylidene chloride-vinylchloride copolymer named Alon 321 (a product of the Toa Gosei Kabushiki Kaisha) which is dissolved into the compound solvent of 300 grams of ace-tone, 100 grams of methyl ethyl ketone, 500 grams of benzene and 100 grams of toluene, and exposed to an air current of 1 'm./min. velocity with humidity of 80% and temperature of 60 F., for approximately one minute before being shifted to a stream of heated air to dry.

-When the film base gets dry and cooled oif, again the photographic emulsion for direct positive reproduction manufactured in known way will be applied on the subbing face. The photographic film base, when dried, turns out to be dimensionally stable film most preferable for reproduction of industrial drawings and most useful for diapositive for printing diazotype papers.

Example 4 A 0.050 mm. thick polyethylene terephthalate film base (obtainable under the brand Diafoil, a product of Nagahama Jushi Kabushiki Kaisha) can be applied with the subbing solution composed of 50 grams of Saran F 220 (Dow Chemical Co. product), 500 grams of acetone and 500 grams of benzene, on one face and dried at temperature of 68 F. in an air current having relative humidity 70%, to mold film. When dried, the solution of hydrophilic colloid (in which cadmium sulfide is contained at the ratio of 0.1 gram/liter for the 5% liquid of hydrophilic colloid) which is composed of gelatine, polyvinyl alcohol and PVM/MA (copolymer of vinyl methyl ether and maleic anhydride, obtained from General Aniline & Film Corp., U.S.A.) at the relative ratio of 3:221. When the second coating dries, apply 1.5% solution of carboxymethyl cellulose containing the conventional concentrations of sodium thiosulfate and sodium sulfite and dry it. This process produces a film usable as positive layer of photocopy widely known as process of Diffusion Transfer Reversal. The product of this process is quite different from the conventional positive film of the same purpose usually made by coating on the cellulose acetate base, being very thin but strong enough to resist tearing and curling (even without backing), and, more significantly the film is free from diffusion during the printing process to diazotype papers.

Example 5 A 0.12 mm. thick soft polyvinyl chloride, which is mostly copolymerized with vinyl acetate such as Astralon UG (a product of Dynamit A.G., Germany), can be applied on its surface with subbing of Alon 321 (instead of Saran F-220), and on the subbing layer with coating of low speed gaslight emulsion which is composed of synthetic resin (chiefly consisting of polyvinyl alcohol as protective colloid) in order to produce inexpensive film for reproduction of industrial drawings. This film is characterized not only with the low cost, but also with the thermoplastic property that will enable, for instance, aerial survey photograph to be easily reproduced into three-dimensional terrain model which possesses realistic appearance in ratio to the true contour lines through the heat molding with three dimensional terrain pattern. This model is useful for industrial, engineering and educational purposes.

6 Example 6 The films produced following the processes prescribed in Examples 1, 3 and 4, can be turned into master paper for offset printer of olfice use through the following process.

Develop the film (produced according to Example 1, 3 or 4) in the usual way to obtain the positive right-hand image. Then put the wet film into the etching bath of combination solutions composed of the following:

(In case the film is dry, soak it in 0.5% acetic acid. The films produced through the processes of Examples 1 and 3 may be put into the etching hath right after the development and before the fixing.)

Add water necessary to make 1 litre after mixing all elements.

Solution B:

Hydrogen peroxide (30%) ml Water ml 900 The listed solutions A and B will be mixed into Water at the ratio of A:B:water=1:1:2, at the normal temperature just before the etching.

When the black image parts comes out on the film face, completely remove the black parts by lightly scrubbing the surface with wet cotton or the like. Washing of the film in 0.5 acetic acid is the final method to produce the master paper for the offset printing.

The theory underlying is that the part of film where the hydrophilic colloid layer is completely removed will expose the face of lipophilic copolymer chiefly consisting of vinylidene chloride. Then only printing ink will attach to the lipophilic copolymer face and it will be rejected from the part where damp hydrophilic layer still remains. Since there is an innumerable amount of holes on the surface of the lipophilic copolymer the oily printing ink will adhere and stay there enabling the master sheet to serve as an excellent printing matrix. Naturally, the size of the matrix depends upon the printing size of the printing machine.

Example 7 Approximately gram/m? thick baryta paper or similar kind of smooth and water-proof base-paper equivalent to it can be applied at its back with the first application of doctor coating of Alon 321, i.e., copolymer of vinylchloride and vinylidene under the normal, but no special, conditions, and with the second applica tion on the surface with the invention method as stipulated in the Example 5. This layer effects increasing water-proofness and at the same time serves as the subbing or underlayer for the ensuing coating of the photographic transfer layer. When the image receiving layer useful for Diifusion Transfer Process is applied in identical way as mentioned in Example 4, and when the paper is further processed in identical way as prescribed in Example 6, the finished product will be an inexpensive master paper for use in offset printing.

Example 8 Approximately 50 gram/m. thru 60 gram/m. thin tracing base paper can be made into transparent photocopy positive paper for use in Diffusion Transfer Process tlu'ough the following method:

Impregnate the tracing paper with the solution of Saran F-220 in methyl ethyl ketone, and when the paper is dried and becomes transparent, process one side of the paper in the manner described in Example 4. This photocopy positive paper while not so strong as the polyester base material of Example 4, however forms an inexpensive and excellent diapositive for diazotype paper printing.

Example 9 Example 8 describes a two stage procedure of impregnating and subbing. This can be effected in one stage as follows:

Approximately 40 gram/m. thin Japanese paper, such as Tengucho brand, can be impregnated with combined solution of:

Alon 321 grams 80 Acetone do 400 Benzene do 300 Toluene do 300 i and longitudinally lifted up from the liquid bath while being exposed to a slow air current of high humidity, to create the microporous surface in accordance with this invention.

After drying, the photographic emulsion will be applied on one side of the sheet as in Example 1, only with chlorobromide emulsion for use of projection printing, and on the reverse side, with anti-halation layer through the identical process mentioned in Example 2. This paper is very useful as diapositive in reproduction of blue print or diazo print purposes for industrial and engineering use, upon projection from the original negatives on micro film.

Example 10 A tracing cloth woven of glass fibre and impregnated and dried with 30% solution of polyvinyl chloride resin has dimensional stability comparable to conventional tracing cloths. The glass fibre tracing cloth will have applied on its surface a subbing layer in the manner described in Example 4 with the characteristic microporous surface. The glass fiber tracing cloth thus subbed is further coated with the same high contrast direct positive emulsion described in Example 3 to produce an article which is storage stable and suitable for reproducing drawings for industrial and engineering use.

Example 11 0.3 mm. thick non-woven fibre basically made of cut fibre of nylon and polyvinyl formal can also be coated on one face with the resin solution as described in Example 9 and dried according to that example to finish the subbing layer. Further application of a gas light emulsion provides a product which yields most attractive portraits. It is especially suitable for color picture papers since the base is readily washed, thus permitting the rapid processing necessary for color printing processes.

What is claimed is:

1. The method of applying a subbing layer to a photographic film base which comprises applying to said base a coating solution of a hydrophobic copolymer containing 5090% vinylidene chloride dissolved in a mixed solvent consisting essentially of (1) an aromatic hydrocarbon and (2) a highly volatile ketone, the proportion of said ketone being 30 to 50% by weight, passing a current of moist air over said coating to evaporate said solvent, said gas flowing at a velocity of from 0.5 to 4 m./sec., at a temperature of from 50 to 85 F., and a relative humidity of at least whereby said solvent evaporates from said coating with the formation of micropores on the surface thereof.

2. A process as set forth in claim 1 in which the subbing layer is applied to both sides of the film base.

3. A process as set forth in claim 1 in which the film base is a highly hydrophobic copolymer sheet.

4. A process as set forth in claim 1 in which the film base is a polyester sheet.

5. A process as set forth in claim 1 in which the ketone is acetone.

6. A process as set forth in claim 1 in which the base is a fibrous sheet.

7. A process as set forth in claim 6 in which the fibrous sheet is impregnated with a hydrophobic copolymer.

8. A dimensionally stable photographic element comprising a photographic film base, a subbing layer of a hydrophobic vinylidene chloride copolymer coated thereon, said layer having the outer surface thereof covered with micropores of a size from 0.1 to 1 micron, and a hydrophilic photographic emulsion layer upon said subbing layer and filling said micropores.

9. A photographic element as set forth in claim 8 in which the film base is a highly hydrophobic copolymer sheet.

10. A photographic element as set forth in claim 8 in which the film base is a fibrous sheet impregnated with a hydrophobic resin.

11. A photographic element as set forth in claim 8 in which the film base is polyethylene terephthalate and the subbing layer is a copolymer of vinylidene chloride and vinyl chloride.

References Cited by the Examiner UNITED STATES PATENTS 2,306,525 12/42 Cummings 11736.7 XR 2,491,023 12/49 Alles et al. 9687 XR 2,494,053 1/50 Mitson et al 9635 XR 2,548,537 4/51 Kenyon et al 9635 XR 2,676,102 4/54 Boyd et al. 117-76 2,698,235 12/54 Swindells 9687 2,698,240 12/54 Alles et a1. 117-76 2,781,265 2/57 Von Mendham 11734 XR 2,848,327 8/58 Ei-chorn 9685 XR 2,878,121 3/59 Gray 9629 2,926,104 2/60 Goetz 11'7 119.8 2,939,802 6/60 Werle et al. 117-119.8 2,957,791 10/60 Bechtold 117-36.7 XR 2,976,168 3/61 Thompson et al 11734 2,993,803 7/61 Sulich et al. 11734 WILLIAM B. MARTIN, Primary Examiner.

RICHARD D. NEVIUS, MURRAY KATZ, Examiners. 

1. THE METHOD OF APPLYING A SUBBING LAYER TO A PHOTOGRAPHIC FILM BASE WHICH COMPRISES APPLYING TO SAID BASE A COATING SOLUTION OF A HYDROPHOBIC COPOLYMER CONTAINING 50-90% VINYLIDENE CHLORIDE DISSOLVED IN A MIXED SOLVENT CONSISTING ESSENTIALLY OF (1) AN AROMATIC HYDROCARBON AND (2) A HIGHLY VOLATILE KETONE, THE PROPORTION OF SAID KETONE BEING 30 TO 50% BY WEIGHT, PASSING A CURRENT OF MOIST AIR OVER SAID COATING, TO EVAPORATE SAID SOLVENT, SAID GAS FLOWING AT A VELOCITY OF FROM 0.5 TO 4M./SEC., AT A TEMPERATURE OF FROM 50 TO 85*F., AND A RELATIVE HUMIDITY OF AT LEAST 70%, WHEREBY SAID SOLVENT EVAPORATES
 8. A DIMENSIONALLY STABLE PHOTOGRAPHIC ELEMENT COMPRISING A PHOTOGRAPHIC FILM BASE, A SUBBING LAYER OF A HYDROPHOBIC VINYLIDENE CHLORIDE COPOLYMER COATED THEREON, SAID LAYER HAVING THE OUTER SURFACE THEREOF COVERED WITH MICROPORES OF A SIZE FROM 0.1 TO 1 MICRON, AND A HYDROPHILLIC PHOTOGRAPHIC EMULSION LAYER UPON SAID SUBBING LAYER AND FILLING SAID MICROPORES. 